This invention relates to the field of art concerning stacking of lumber by automation and more particularly to mechanisms for moving a reciprocating carriage between a course pick-up station a course stacking station.
Many lumber stackers, including the one disclosed in Lunden, U.S. Pat. No. 3,437,215 granted Apr. 8, 1969, utilize a fork arm assembly that is sequentially moved (1) upward at a course formation or pick-up station to pick up a course of boards or lumber, (2) forward to a course stacking station, (3) downward in front of a stripping mechanism, and finally (4) rearward to strip the course from the arm assembly to remove the course and allow the course to fall onto the stack.
Generally the forked arm assembly is carried on a reciprocating carriage that is moved back and forth in a track arrangement. The greatest energy requirements in moving the carriage occur during the initial phase of the forward and back stroke in which energy is required to initiate acceleration of the carriage. Also, additional energy is required to raise the forked arm assembly at the beginning of the forward stroke and to strip the course off the arm assembly at the beginning of the rearward stroke. Furthermore, additional energy is required to overcome the frictional loss of the carriage as it moves in the track arrangement.
One of the principal objects of this invention is to provide a unique carriage drive system that reduces the energy requirements in moving the carriage plus enables the carriage to be moved at a smooth acceleration at the beginning of the stroke and at a smooth de-acceleration at the end of the carriage travel.
An additional object of this invention is to provide unique carriage drive system for lumber stacking apparatus that not only conserves energy but is relatively inexpensive to construct and requires less maintenance.
A further object of this invention is to provide a lumber stacking apparatus having a unique carriage drive system that reduces the horsepower requirements in operating the device and which is capable of storing energy for subsequent use in the operation.
A still further object of this invention is to provide a lumber stacking apparatus having a very smooth carriage drive system that is capable of storing energy both at the beginning and end of reciprocating strokes.
These and other objects and advantages of this invention will become apparent upon reading the following detailed description of a preferred embodiment.